Chicco KeyFit 30. We registered for the Travel System at BRU based on a friend's recommendation who had a baby prior to my daughter. She also demonstrated how easy it was to operate both the infant seat & the stroller. We used this travel system with my DD who was born last year & I really liked it. It was a breeze to use for Mommy, Daddy & Grandma. I liked how the seat just snaps into the base & the Cortina stroller. Although my DD still could use this infant car seat because she's only 20lbs at 15 months old, we have already transitioned her over to a Britax Boulevard 70 CS in anticipation of the new baby arriving. Per their website, "#1 Rated Chicco KeyFit is the easiest car seat to install correctly" and I have to attest that I believe this based on our travels - as a first time mom, I was able to confidently install this car seat in other cars when we flew to see my family when my DD was just 3 months old.